def usage: Exceeds column 80

Details

There are very long lines in 'def usage' like below.
Please make all lines fit on 80 column for easy
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DESCRIPTION
filter spam.
If commands are specified, bsfilter is in
maintenance mode, otherwise it
is in filtering mode.
If bsfilter does not find spam in filtering
mode, exit status is 1.
If bsfilter runs with --pipe option or finds
spam, exit status is 0.